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After anterior resection of the rectum (AR) with lymph node dissection, change in bowel habit is often observed even after recovery of the anorectal function possibly due to changes in colonic motility after the operation. This study was to investigate the relationship between the degrees of extrinsic autonomic nerve injury and the changes in colonic motility. [Methods] Twelve mongrel dogs were equally divided into four groups and underwent implantation of 5 serosal electrodes on the colon. Group A had denervation of autonomic nerves in the paraaortic and presacral regions, including hypogastric nerve and pelvic plexus, from the level of the axis of the caudal mesenteric artery (CMA) to the pelvic space. Group B had denervation in the paraaortic region from the axis of the CMA to the bifurcation of the iliac artery. Group C had denervation by dividing the mesocolon along the marginal artery from the CMA to the peritoneal reflection. Group D had only electrode implantation. Electromyogr
… Moreaphic activity was measured continuously during 30 minutes in interdigestive state and 120 minutes after injection of olive oil through gastrostomy. The number of continuous electrical response activity (CERA) and contractile electrical complex (CEC) were counted in every ten minutes. [Results] Three weeks after the operation, colonic CERA and CEC in the period from 20 to 30 and 30 to 40 minutes after the olive oil injection was smaller (p<0.05) in Group A (2.2<plus-minus>0.72,3.4<plus-minus>1.12, respectively ; mean<plus-minus>SEM) than in Group D(10.6<plus-minus>1.97,10.8<plus-minus>2.24). This difference was present even in the right-sided colon (Group A : 0.4<plus-minus>0.28,0.6<plus-minus>0.40 ; Group D : 4.3<plus-minus>0.98,4.3<plus-minus>0.91 ; p<0.05). On the other hands, CERA and CEC in the interdigestive state in Group B (8.8<plus-minus>1.87)and C(7.6<plus-minus>1.45) were increased (p<0.05) as compared with Group D (5.2<plus-minus>0.83).Four months after the operation, increased colonic motility in Group B and C returned to the level of Group D,but the low colonic motility was still observed in the right-sided colon in Group A (0.8<plus-minus>3.32,0.4<plus-minus>3.32 ; p<0.05). [Conclusions] Pelvic plexus plays an important role in colonic motility even of the right-sided colon. The damage to theparasympathetic presynaptic neurons did not recover at least until 4 months after denervation. These data suggest that the pelvic plexus injury may cause the change in bowel habit after AR Less